It is well known that, in a communications network, power of a signal received by a terminal is directly affected by an environment in which the terminal is located. In a relatively harsh environment, a terminal that originally can perform communication normally cannot perform communication normally due to excessively low received signal power.
For example, in a same area within coverage of a same base station, power of a signal received by a terminal located in a basement is generally lower than power of a signal received by a terminal located outdoor.
To enable a terminal located in a harsh environment to perform communication normally, a method for performing enhanced transmission on system information required in a communication process of the terminal is used to ensure normal communication of the terminal. The enhanced transmission refers to that information that needs to be transmitted to a terminal is transmitted in multiple subframes for multiple times to ensure that the terminal can receive complete information.
However, in the method for transmitting system information, because multiple subframes (which may be several hundreds of subframes) need to be occupied to transmit the system information, many transmission resources are occupied in a process of transmitting the system information. In a mobile communications system, available transmission resources are limited for the system; therefore, if system information is continuously transmitted in an enhanced transmission manner to a terminal located in a harsh environment, resource overheads are excessively large, leading to insufficient resources for transmitting downlink data by a terminal not located in a harsh environment.